The market demand for smaller and more powerful electronics continues to fuel development of semiconductor devices that make such electronics possible. Efforts to maintain performance levels of semiconductor devices constantly face new challenges as device geometries get smaller. Technologies for which higher device performance is required can conflict with scaling efforts. Silicon-based semiconductor devices have been widely developed, but silicon-based technologies have reached physical limits that make it necessary to explore alternatives to meet demands for size and performance. Gallium-arsenide (GaAs)- and gallium-nitride (GaN)-based semiconductor devices, which have been less widely used than silicon-based devices, can reach smaller geometries without the problems seen in semiconductor devices. In addition, GaAs and GaN devices are capable of switching at higher speeds and conducting higher levels of current. However, GaAs and GaN device development has also encountered obstacles in both design and fabrication with regard to meeting performance objectives at smaller geometries, so new fabrication processes are needed.